I recommend using level 14 in chapter 2.
Kill the sniper to the north-east and the first 3 soldiers to the east. Grab the intel and dog tags if you like for 750 command points.
Call in an airstrike package for 24000. Head north and kill the guy standing on his own up a small set of stairs and head towards the health kit. You can pick it up to help you stay alive for this bit. Move to the box of rockets and move around this area avoiding enemy fire and a large amount of soldiers will gather, about 10-15. Drop an airstrike right in the middle and you should get at least 10 kills. Then if you head west there will be a few more soldiers and also to the north unless they already came down with the rest. This should take no more than 3 runs on this level if you are accurate. Costing only 72000 command points.